Influence Of Continuous Application Of Biogas Slurry On The Microbial Characteristics In Rice-Rape Rotation Operation Soil

Biogas project was the main way to utilize biomass energy efficiently in rural areas, biogas slurry produced after anaerobic fermentation residue was rich in nutrients needed for plant growth and activity resistant material to stimulate crop growth, was a liquid organic fertilizer both fast and slow-release, reasonable utilize biogas agricultural promoted crop growth, improved soil quality of the environment, reduced agricultural production costs, while alleviating pressured slurry subsequent processing.In this study, the biogas slurry used as irrigation fertilizer was completely anaerobic fermentation, in successive three years rice-rape rotation on the rice-planted yellow soil in Heishi village of Sichuan Province. Twelve treatments have been made (one control applied with clean water, one applied with conventional fertilizer, and ten applied with different quantities of pure biogas slurry), collected soil samples from 0-60cm soil which had been used for rice-rape rotation for continuously three years, research on the microorganism characteristics of rice-rape rotation soil after the continuous application of biogas slurry. The main conclusions are as follows.(1) Continuous application of biogas slurry could effectively increase the number of 0-60cm soil microorganisms, and did not affect the distribution of the vertical space, biogas slurry instead of chemical fertilizer could provide abundant nutrients for the growth of soil microorganisms; with the increasing of biogas slurry fertilizer, soil microorganism in different depth varied, activity of bacteria in the soil of 0-60cm we re increased; the number of fungi in the 0-40cm first increased and then decreased, all reached the maximum value when the biogas slurry amount was 495.31t/hm2, the number of fungi in the soil of 40-60cm had no obvious change; the number of actinom ycetes in 0-20cm soil first increased and then decreased and reached the peak when biogas slurry applying amount was 626.10t/hm2, in the 20-40cm the number increased, in the 40-60cm the number decreased;(2) To analysis soil DGGE obtained that, biogas slurry applying did not favor the rich diversity of soil bacterial community, when the biogas slurry total quantity control in the range of 339.31-396.81t/hm2 bacterial community diversity increased, the bacterial population feature rich, complex information, population stability, too high or too low biogas slurry would significantly reduced the bacterial community diversity; to analysis UPGMA, soil bacterial genetic similarity reduced the long-term continuous slurry application, the structure of bacterial populations changed significantly.(3) Continuous application of biogas slurry could effectively activate soil enzymatic activities, accelerate topsoil soil carbon, nitrogen and phosphorus cycling rate, improve soil quality. With increasing biogas fertilizer, soil urease and invertase activity was lower elevated further reduce the variation trend, and reached the maximum value when the total biogas slurry content was 495.31t/hm2, catalase and phosphatase was elevated after decreasing trend, and reached the peak when the amount of biogas slurry were at 546.32t/hm2 and 339.31t/hm2;(4) The degree of fertilization effected on soil enzyme activity are different, then leaded to soil enzyme activity space distribution changes, the long-term application of fertilizer changed soil catalase activity distribution, with increasing of soil depth increased; biogas slurry applying changed urease and invertase activity distribution, the higher the biogas slurry fertilizer treatment (the application amount higher than 546.32t/hm2) spatial distribution of soil urease activity decreased first and then increased with the increase of soil depth, urease activity in 40-60cm was higher than that of 0-20cm, soil invertase activity and soil depth is inversely proportional to;(5) Biogas slurry treated 0-20cm soil microbial quantity and enzyme activity lev el, but the bacteria/fungi (B/F) ratio decreased, it indicated that long term application of biogas slurry may exist in the soil to the low fertilizer high damage "fungus" conversion risk;Based on the above, micro ecological environment was not destroyed, the number of soil microorganism, soil enzyme activity increased, the bacterial population stable when three years successive application of biogas slurry total quantity control in the 396.81t/hm2 (BS4) around the soil.